1. Field of the Invention
The present invention relates to the technical field of image processing and, more particularly, to a de-interlacing system with an adaptive edge threshold and the interpolating method thereof.
2. Description of Related Art
Due to the limitation of broadcast bandwidth, current TV broadcasting typically uses alternate odd/even fields. As shown in FIG. 1, odd fields 10 and 12 have only odd-line video data, and even fields 11 and 13 have only even-line video data. A line doubler is required in a new-generation TV to perform a double frequency processing for meeting with the increased vertical resolution. The simplest double frequency processing directly merges tandem odd and even fields to thereby form a progressive scan frame. However, because of a time difference between the tandem odd and even fields, such a processing introduces a sawtooth to a moving object image.
Since such a processing introduces a sawtooth to a moving object image in the dynamic picture, the prior art determines if the field currently used is the motion picture in order to overcome the aforementioned problem. When the field is the motion picture, a single field is interpolated as a frame to avoid the sawtooth. When the field is not the motion picture but a still picture, tandem odd and even fields are merged for use to thereby avoid a flicker.
Typically, images are determined as motion pictures by a fixed threshold. When the amount of motion is greater than the threshold, the images are determined as the motion pictures. When the amount of motion is smaller than the threshold, the images are determined as still pictures. However, such a fixed threshold can cause a mistaken determination when the images come from different sources or pictures.
To overcome the aforementioned problem, U.S. Pat. No. 7,027,099 B2 has disclosed a method, which analyzes whether an image is of a motion picture in frequency domain, thereby avoiding the mistaken determination. However, such a method requires changing the image into the frequency domain, which relatively increases the computation amount and causes the cost.
Therefore, it is desirable to provide an improved system and method to mitigate and/or obviate the aforementioned problems.